The present invention is related to aircraft air conditioning systems, and in particular to a system and method for detecting contamination within air conditioning systems.
Aircraft often include air conditioning “packs” that, among other things, provide cool air for the aircraft. These aircraft also may include one or more ram air fans that draw air through the air conditioning packs while the aircraft is grounded. The ram air is drawn through, for example, heat exchangers of the air conditioning packs. Contamination from the ambient air may increase the pressure drop across the heat exchangers which may reduce the flow through the fan and heat exchangers. Significant heat exchanger contamination can reduce the airflow enough that the ram air fan may operate in an unstable operating mode which may lead to excessive blade stress and in turn, failure of the ram air fan.